[FEAT] 優化客戶合約管理介面與修復日期偏移問題

1. 整合「客戶詳情」與「合約歷程」至單一側邊欄，改用分頁 (Tabs) 切換介面。
2. 優化清單「服務期程」顯示：根據客戶模式（租賃/買斷）動態顯示對應期間，並使用完整文字標籤取代縮寫。
3. 修復日期 Bug：在 Company 模型指定日期序列化格式為 Y-m-d，解決時區轉換導致的日期減少一天問題。
4. 新增合約歷程資料表模型、遷移檔以及對應的多語系翻譯（中、英、日）。
5. 移除清單操作列中重複的合約歷程圖示。

database/migrations/2026_04_08_164500_add_contract_dates_to_companies_table.php

@@ -0,0 +1,36 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('companies', function (Blueprint $table) {
+            $table->date('warranty_start_date')->nullable()->after('end_date')->comment('保固起始日');
+            $table->date('warranty_end_date')->nullable()->after('warranty_start_date')->comment('保固結束日');
+            $table->date('software_start_date')->nullable()->after('warranty_end_date')->comment('軟體服務起始日');
+            $table->date('software_end_date')->nullable()->after('software_start_date')->comment('軟體服務結束日');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('companies', function (Blueprint $table) {
+            $table->dropColumn([
+                'warranty_start_date',
+                'warranty_end_date',
+                'software_start_date',
+                'software_end_date'
+            ]);
+        });
+    }
+};

database/migrations/2026_04_08_165000_create_company_contracts_table.php

@@ -0,0 +1,39 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('company_contracts', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('company_id')->constrained()->onDelete('cascade');
+            $table->string('type')->comment('buyout, lease');
+            $table->date('start_date')->nullable();
+            $table->date('end_date')->nullable();
+            $table->date('warranty_start_date')->nullable();
+            $table->date('warranty_end_date')->nullable();
+            $table->date('software_start_date')->nullable();
+            $table->date('software_end_date')->nullable();
+            $table->text('note')->nullable();
+            $table->foreignId('creator_id')->nullable()->constrained('users');
+            $table->timestamps();
+            
+            $table->index(['company_id', 'created_at']);
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('company_contracts');
+    }
+};